VM: expose exact active legacy arguments for compiled ordinary functions

[chrisbbreuer]

Parent: #465. Found while validating #801; coordinate activation ownership with #787.

Baseline e4f76af fails this positive paired VM witness even without GC:

function legacyRead(value) { return legacyRead.arguments[0]; }
assert.sameValue(legacyRead(37), 37);

The tree-walker passes; required bytecode throws TypeError: null is not an object. The ordinary function is admitted, but VM calls do not publish the legacy call-frame view used by Interpreter.getProperty. This is separate from relocation of an already published tree-walker legacy frame.

Acceptance:

• Preserve the engine's legacy caller/arguments behavior in admitted ordinary compiled calls, including inline, nested-driver, recursive and tail transitions, without routing them to the tree-walker.
• Keep argument mapping/identity, strict and newer-function poison restrictions, and cross-realm behavior exact.
• Publish and retire introspection views under the existing activation ownership protocol, failure-atomically and with relocatable function/environment/argument slots; coordinate with GC: publish provisional VM activation roots failure-atomically #787 rather than racing that lifecycle work.
• Add no-GC and actual moving-GC differential controls, OOM, no-GIL/TSan and relevant conformance.

The failing witness and transcript are retained locally under /Users/chris/.cache/zig-js-801.9pDs7h/legacy-arguments.js and before-legacy-arguments.log. This issue remains open independently of the scoped coercion/assignment root work.